This disclosure relates to assemblies for dampening rotary motion such as, for example, damper pulleys for use with automotive internal combustion engines.
In order to reduce the effect of torsional vibration during power transmission in automobiles, pulley mechanisms have been developed with internal dampeners. These dampeners help to dissipate spikes in the transmitted energy and to absorb vibrations that occur during rotary motion of the pulley mechanism.
Dampening pulleys are conventionally made from two cast iron parts which are bonded together with rubber. Usually, an inner hub and an outer ring are first cast. Then, one or both of the parts may be machined. Typically during machining, a raised annular lip is formed in the outer diameter of the hub and an annular recess is formed in the inner diameter of the ring, although these features could be reversed. Then, to assemble the pulley, the hub is placed inside the ring such that faces having the machined annular lip and recess oppose one another and rubber is molded or placed between the cast metal parts to bond the two metal parts together and to establish a dampening element in between the two metal parts.
However, machining operations such as those used to form the annular lip and recess can be expensive and time consuming. Moreover, the bond between the cast metal parts and the rubber can limit the quality and ability of the assembly to perform its dampening function. Hence, there is a continued need for improvements in assemblies for dampening rotary vibrations created during power transmission and for improved methods of making such assemblies.